Telephony.



E. R. conwm.

TELEPHONY.

APPLICATION TILED APR. 5| I913- 1, 173,773. Patented Feb. 29, 1916.

2 $HEETS-SHEET I.

. mvE 'roR W FIG 1 g m R. ORMN ATTWNEY E R. CORWIN.

TELEPHONY.

APPLICATION FILED APR.'5. 191s.

Patented Feb. 29, 1916.

' 2 SHEETS-SHEET 2.

WIT 6 NE SES ELMEE 1ft. QGRWEN, 0F CHIUAGG BY MESNE ASSIu-NMENTS, T8

FRANK 1'5. @063 GOIEPANY, G UHICAGG, ILLINOIS, .Pi; CORPORATION OF ILLINOIE.

TELEPHQ'DPZ.

1 173 73 Specification of To all whom it may; concern Be it known, that L Emma R. Coawsn, citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful improvement in Telephony, of which the following is a full, clr-zar concise, and exact description, reference being had lo the accompanying drawings, forming a part of this specification.

' My invention. relates to telephone exchange systems and has 'a niiunber of objects and advantages in view.

My invention finds an important embodiment in so-callcrl automatic telephone exchange systems where calling subscribers are enabled to effect connection between their lines and desired lines, though the invention has many characteristics which are not to be limited to systems of this class as will be apparent from'a full description of one embodiment of the invention that is to be given.

My invention has for one of its objects the provision oi link connectors and electromagnetic switches for connecting the link connectors with lines and also with other link connectors which are controlled by the talking sides of the link connectors independently of third conductors.

My invention has for another of its objects the provision of electromagnetic means operating normally to divide the link connectors into sections whereby traveling members which are used to extend telephone lines and link connectors may remain in contact with the waiting contacts they were caused to engage in establishing connections when the connected parties are through convcrsation whereby stepping up and releasin mechanism individual to the link circuit may be dispensed with.

lily invention has for another of its objects the provision of master switching mechanism common to the link connectors or telephone conductor sections of a group, additional link connectors or telephone conductor sections switching devices for connecting the latter link connectors or telephone conductor sections with the former and setting up switching mechanism for bringing these switching devices within the control of the circuits with which the master switching mechanism is associated .whcre'oy desired extensions may he applied Tfietters Patent.

Serial No. 759,020.

to calliiig lines without the aid'ofstepping up devices and releasing niecl'ianism for rc storing the "equipi'nent to normal.

My inventioi'i has for another of its obects the provision of means whereby signaling current may be withheld from desired lines that previously busy and may be antoiaatically applied to such lines when they havebaen restored to normal at their substations.

The abovevohjects of my invention spccificallystated but the invention is not to-be limited thereto as these objects and other objects and-advantages will be appreciated by reference'to the accompanying drawings, showing; the preferred cmbodiinent thereof and in which Figures 1 and 2, taken collectively and in their numerical order with the conductors at the right and left hand sides thereof in alinement, illustrate a telephone exchange system equipped in accordance with the preferred embodiment of the invention.

1 have shown two substations 200 and 201 whose lines, for the sake of simplicity in explaining the invention, are illustrated as extending to the same exchange. Each substation includes well known telephone are hook 1, a call hell 2, a condenser 3, a telephone receiver 4, and a telephone transmitter 5, the telephone switch hook having a ncrmalcontact for including the bell and condenser in bridge of the associate tele phone line when the receiver is upon the switch hook andv having an alternate contact for including the receiver 4 and t 'ansmitter 5 in bridge of the associate telephone line when the switch hook is free of the telephone receiver. The limbs of the telephone lines terminate in waiting contacts 6 and 7, there beinga plurality of each of these contacts for each line and which are multiply related, a pair of contacts 6, 7 being included in each of a number of switches that are employed for extending the telephone lines. Each telephone line is shown with two pairs of contac 6, '7 with the wipers 8, 9 of such a switch and two other pairs of such contacts 6, 7 that are not shown with wipers 8, 9 resting in engagement therewith, the two upper pairs of waiting contacts being passed over by the wipers 8, 9 of the upper switch i) and the two lower pairs of these waiting in connection 7 .10 The wipers 8, 9 of each switch constitute terminals, of link connectors and which terminals are operated to connect calling lines with the link connectors having such terminals. Thus each wiper 8 is connected With one side 10 of a link connector and its companion 9 is connected with the other side 11 of such link connector. Each link con nector side 10 has a waiting contact 12 complemental to the terminal 8 of such link con- 2o nector side and each link connector side ll has a waiting contact 13 complemental to the terminal 9 of such link connector side. The Waiting contacts 12 and 13 of each link con- 'nector are in multiple connection, respectively, with similarly positioned contacts, these contacts 12 and 13 being distributed among a number of secondary selector,

switches having wipers 14 and 15, each pair of wipers 14, 15 passing over a number of pairs of waiting contacts 12, 13 belonging to diiierent link connectors. Each wiper 14 is connected with one side 16 of a link connector and its companion 15 is connected with the other sidev 17 of such link connector. Each link connector side 16 has a wiper 18 eomplemental to the terminal 14 of such link connector side and each link connector side '17 has a wiper 19 complementalto the ter; minal 15 of such link connector side. Wipers 18 and 19 in each link connector 16, 17 constitute parts of a connector switch which is operated to bring these wipers into connection with the waiting contacts 6 and 7 that pertain to desired or called lines. A connection which is established between calling and calledv stations includes, by means of mechanism to be described, the calling line, its waiting contacts 6, 7, the wipers 8, 9 of a rst or primary selector switch, the associate link connector 10, 11, the waiting contacts 12, 13 of this link connector, the wiping contacts 14, 15 of a secondary selector.

switch, the link connectors 16, 17 having these wiping contacts 14, 15, the wiping contacts 1 8, 19 of the link connectors 16, 17, and the waiting contacts 6, 7 of the desired line, The pairs of wipers 8, 9, 14, 15, 18 and 19 are preferably limited to single planes of rotation, these wipers being caused to travel by associate ratchet wheels 20, 21-and 22 which in turn are respectively operated by motor magnets 23, 24 and 25 to bring the wipers into association with the proper waiting conand desired lines nto connection.

- line selector switches when the link connector 10,

tacts to be employed for extending calling Each link connector 10, ll has a calling line selector switching device 8, 9, 20, 23 individual thereto and these link connectors and their associat selector switching devices are desirably divided into groups of, for example, ten to take care of the trafiic for one hundred lines. This group of link connectors 10, 11 together with the group of calling pertaining thereto is provided with a master switching device common to such link connectors and their calling line selector switches, there thus. being one such master switching device to each group of ten link connectors 10, 11. This master switching device includes wipers 26, 27, 28, 29 and 30 each common to its group of link connectors 10, 11 and these wipers are respectively provided with as many sets of waiting contacts 31, 32, 33, 34and 35 as there are link connectors 10, 11, there thus being, 'in the example chosen, ten of such waiting contacts 31, ten of 32, ten of 33, ten of 34, and ten of 35. The wipers 26 to 30 are desirably caused to move in single planes ofrotation by means of a ratchet wheel 36 ,90

operated by tionship of the ratchet wheel 36 and motor magnet 37 being such that the wipers 26 to 30, when normal or idle, are in electrical connection with the waiting contacts 31 to" 35 of some link connector 10, 11 in the 'group to which the wipers 26 to 30 pertain, these wipers stepping off the contacts with which they happen to be connected into connection with the succeeding set of waiting contacts 11 having the first set of Waiting contacts has become connected with the succeeding extension such as 16, 17, the wipers remaining in connection with these second named waiting contacts until another call is'initiated where upon these results are repeated. Each master electro-magnetic switching mechanism 36, 37 has a setting up switching device individual .thereto and which is employed for the purpose of establishing connection between the employed link connector- 10, 11 and the succeeding link connector 16, 17. This setting up switching mechanism includes a pair travel by a ratchet wheel 40 from a fixed position, to which fixed position these wipers are returned when they are no longer to perform their function in establishing a con-, nection. The ratchet wheel 40 is operated by a motor magnet 41 and is permitted to reof wipers 38, 39 caused to L a motor magnet 37, the relay store to normal by a restoring magnet 42 I, each common 1 ratchet wheel brin connecto l contacts 4-3, are individual to dil'lerent groups of link connectors 1 17. Each link connector 16, has a calling secondary selector switching device 1%, lo, 21, 24; individual thereto and these link connectors and their associate secoi'idary selector switching devices are desirably divided for example, ten. Each group of link connectors l6, 17 together withthe group of second selector switche pertaining thereto is provided with a master switching device common to such link connectors and their secondary selector switches 141-, 15, 21 and the e d to each group of ten link connectors l6, 1?. This master switching device includes wipers if), 46, l7, Q8, 41 9 and 50 to its group of link connectors these wipers are respectively video with many of waiting contacts 51, 53, and there are-link con nectors 1c, 1?, there thus being, in the ere ample chosen, ten such waiting contacts 51, ten of 52, ten of 53, ten of 54-, ten 01'? and ten'oi The wipers L55O oesirably caused to more in single planes of rotation by means of a ratchet wheel 57 operated by a motor magnet 58, the relationship of the and motor magnet 58 being such that the wlpers i550, when normal or idle, are in electrical connection with the waiting contacts 516 of some link connector l6, 17 in the group to which the wipers e5-50 pertain, these wipers stepping off the contacts with which they happen to be connected into connection with the succceding set of waiting contacts when the link connector 16, 17 having the first set of waiting contacts has become connected with the succeeding extension such as the desired line, the wipers remaining in connection with these second named waiting contacts until the new link 1 1'? has become con-l 16 l and nccted with another desired orcalled line whereupon these results are repeated. liach master electromagnetic switching mecha-- nism 5T, 58 has seting up switching device individual. thereto and which is employed for the purpose of establishing connection between the employed link connector 16, 1'7 and a succeeding ision for the calling line, such :tor example desired or called line, This setting up switching mechanism includes a wiper causec to travel by a ratchet wheel 66 from position, to which. position this w i": no when it is no longer to *orni it in establishing a coi'inection,

into groups of,

thus being one such master switch- J a motor magnet 61 to restore to normal by a storing magnet 62 when this latter magnet energised to attract the actuating pawl of the .motor magnet (31 f om engagement with the ratchet wheel. By means oi apparatus described the wiper 59 is brought into connec on with a waiting contact 63 that individual to the line portion with which the link connector 16, 17 is to be connected, in this instance the called. line, whereby the motor magnet may be operated to bring the wipers 18, 19 of the employed linli connector 18, 17 into engagement with the waiting contacts 6, '7 of the desired line.

The primary selector witch 2G, 23 that happens to be electrically associated with the master switch 37 is kept in constant operation until the wipers 8, '3, encounter the sides of a calling line, the circuit that causes such ope-ration of this primary selector switch being; traceable from the common grounded, battery 61, the interrupter (35 that intermittently opens and closes this circuit, the switch spring 66 and its normal contact, the left hand ari'nature switch of the sluggishly operating relay 6? and its contact, the wiper 26, the waiting contact 31 that happens to be engaged by this wiper and individual tothe motor magnet 23 that is being operated, the winding ot this motor magnet 23-, the intermediate armature switch of the relay 68, to ground. Nhen a sul scribcr initiates a call he first removes his telephone receiver from its switch hook, thereby establishing a circuit, when the moving wipers 8, 9 encounter the waiting contacts t3, 2 of the calling subscribers line, which circuit be traced from the grounded battery 6 through the winding of the sluggishly operating relay 67, the wiper '27, the waiting contact 32 then oils gaged by the wiper 27, the uppermost switch of the relay 68 and its normal follow-up contact, the wiper 8 which was in motion, the

waiting contact 6 of the calling line, both sides of the calling line, the waiting contact 7 of the calling line, the wiper 9 which was in motion, the lowermost armature switch of relay 88 and its normal followup contact, the wiper 28 and the waiting contact 33 then engaged thereby, the relay 69, to ground The reley G7 is now energized, its left hand armature switch opening the circuit for the motor magnet 23, previously traced, whereby the wipers 8, 9, that were moving are brought "to rest in connection with the waiting contacts 6, 7 of the calling. line. The relay "(39 is now energized once,

the armature switch of this relay closing a,

move the ratch w eel. l0 step thereby to permit the s; ring 68 to l ase its iiorinal e its alter- 1-: contact, the 8 switch Gtlfrrom its normal contact occasioning a second gap in the cir- .Cuit of the interrupter 65 for the sake of assurance, the wipers 38, 39 being at this time incidentally moved one step without engaging anyfwaiting contacts 43, 44. The

lines are normally free of battery, a calling ing mechanism, suchas a dial mechanism,

this circuit interrupting mechanism being diagrammatically illustrated at 70. The device 70 is manipulated the number of times which is required to bring "the wipers 38, 39 into engagement with that pair of waiting contacts 43, 44, individual to a link connector 16, 17 that is provided with a connector switch 25 having waiting contacts 6, 7 which pertain to the desired line. It is understood that the link connectors 16, 17 may extend to different exchanges and are to be selected by the calling subscriber accordingly or they may extend to different groups of telephone lines in the same exchange. From a circuit previously traced this result is accomplished by opening and closing the circuit of the relay 69 by the switch 70 the predetermined number of times to bring the wipers 38, 39 into engagement with the proper waiting contacts 43, 44. The circuit governed by the relay 69 may be traced from the grounded common battery 64, the armature switch of relay 69,

' to the grounded motor magnet 41. When the wipers 38, 39 have been engaged with their proper waiting contacts 43, 44 they, of course, remain in engagement with such contacts-during the establishment of the connection of the. desired link connector 16, 17 with the linkconnector 10, 11, the wipers 38, 39 in passing over other waiting contacts 43, 44 not having opportunity to make any effective circuit changes. 1V hen the Wipers 38, 39 have thus been arrested during the cessation of the operation of the switch in engagement with the desired waiting contacts 43, 44, a circuit is established which is traceable from the grounded battery 64,

through the interrupter 65, the switch 66 and its then engaged alternate contact, the wiper 39, the waiting contact 44 then engaged thereby, the left hand armature switch of relay 71 and its then engaged con- .tact,,thesetting up switch wiper 45, the

waiting contact 51 engaged by this wiper, the motor magnet 24 of the secondary selector switch, the intermediate armature switch of the relay 72 and its left hand follow-up contact, to ground.

The motor magnet 24 is thus operated until its wipers 14, 16 engage the Waiting con-i tacts 12, 13 of the link 10, 11 now connected with, the calling line whereupon a clrcuit is established for the relay 68 which is traceable from the battery 73, through theright hand armature switch of relay 67 and its alternate contact, the wiper 29, the waiting contact 34 that is engaged by this'wiper, the

lower winding of relay 68, the waiting'contact 13, the wiper 15 of the employed secondary selector switch 21, 24, the lowermost armature switch of relay 72 and its normal follow-up contact, the waiting contact 53 in dividual to the employed linl -'connector 1 6, 17, the wiper 47 engaging the waiting con-" tact 53, the left hand winding of relay 71,

the second armature switch from the left helonging to the relay 71 and the follow-up contact of thisarmature switch, the waiting contact 43 individual to the employed link connector 16, 17, the wiper 38 now engaging this waiting contact 43, the now released switch 74 and its now engaged contact, the

winding of the release magnet 42, back to the battery 73. The relay 71 is thus energized and the left hand armature switch of this relay opens the circuit of the employed motor magnet 24 to keep the wipers 14, 15 individual thereto in connection with the waiting contacts 12,13 of the link connector 10, 11 that'is connected with the calling subscriber. The release magnet 42 was included in the circuit just traced so that the ratchet wheel 40 is restored to normal permitting this ratchet wheel and the setting up switch of which it formed a part to be emploved in setting up a new connection when initiated, the circuit of the motor magnet 41 being now open owing to the shifting of the Wipers 26 30 to their engagement with waiting contacts 3135 of a succeeding set of waiting contacts pertaining to an idle link connector 10, 11 by a circuit traceable from the grounded battery 64, the motor ma net 37, the wiper 30, the waiting contact 35 first engaged by the wiper 30,the intermediatearmature switch of .relay 68 and its alternate contact,'to ground, the motor magnet 37 operating one step if the next succeeding set of waiting contacts 31, 35 pertain to an idle contact so that the motor ma net 37 is again energized, the wipers 26-30 thus continuing in movement until they engage idle waiting contacts. The opening of the motor magnet 41 occurs at the armature switch of relay 69 when thus dei nergized. The relay 67 is slu'ggishly operating so that the relay 69 may be rapidly operated in responding to the movements of the switch 70 while the armature switches of the relay 67 remain in their attracted positions. If the calling subscriber should change his mind end not de-l sire to extend his telephone line into eonnee tion with another line and 1102 having operated his dial 70, such subscriber will merely restore his receiver upon its switch. hook whereupon circuit will be esilablishcd through the release magnet; to restore the wipers 38, 39 to their normal-or zero position, such release magnet circuit, being trace ehle from the battery 73, the right hand iii-nurture switch of relay (Slund its normal contact, the switch is and its then engaged contact, the release magnet 42, back to the cattery 73. A loclring circuit is established r the relay 68 which is traceable from the e ounded buttery G hrhe upper winding of relay 68., the lefe hgnd alternate contact of the uppermost armature switch of relay. 68, this uppermost armature switch, "rho right hand alternate contact of this iii-mm cure switch, the wei contact 12, the wiper 1- now engnf 1,5 the contact-12, the

.9 v uppermost armature switch of relay 72 and,

its normal follow-u}; contact, the waiting contact 52, the wiper #26, the armature swifich ll'lllllfllilill'jly to the right ofthe windiiigs of the sluggishly operating relay 7i and the contact now e g god by this armature h, the right hzrnd winding of reh c ieil; e ale. w of relay ground, i he relay by e circuit (which is a 1 i for relay 75,; traceable r cm the grounded terminal thereof through the winding of the relay iii-the second armature switch to the right of the windings ol. relay 71, the cnnot then engaged by this armature switch, the wiper l7, um. Vflltln contact 525 then engagecl by the wiper $7, The lowermost urinaiure SWi-Ich of relay 72 and its normal l'ollow-np contact. a portion of the link conductor 17 iii a wiper 15, the waiting contact 13 now .i by the wiper 15, the lower most Si ore switch of relay 63 and its eltern: 17c conical, J, employed wiper 9,

i J ti wailing eontece 7 of by the wiper 9, both the wailing contact 6 the calling 1 no, the ..iper 8 or U iging said waitn gr cents I 3, the iipperniosc armature switch of reluy GS end its left hand alternate contact, the winoi of relay 68, 110 one ground very Gel.

The calling subscriber will continue operation of the swiJ ll 70 to bring wipers 18, 19 of fihe employed link coon 16, 1? into connection with the-waiting tocts (3, '7 of the desired line. The su-irch 70 will now be operated to interrupt the circuit of the motor uic'net 61 the nionher of times predetermined by the calling subscriber to bringthe wiper 59 into engagement, with the waiting contact 63 of the desired line. the switch 70 operating di the calling line engaged fl of the caiuig line rectly open and close the circuit of the has been brought into engagement with the selected waiting eontecib 63 e circult is established for the motor magnet 25 which includes the grounded battery 64, the interrupter 65, the switch spring 76 and the contactengaged thereby when the ratchet wheel has heen moved the first step from normal, the wiper 50, the waiting contact 56, the winding of the motor magnet 25, and the intermediate grounded armature switch of the relay 72 and its right hand normal follow-up contact. The motor magnet 25 willthus be operated until its wipers i8, 19 are brought into connection with the waitinc; contact 6, 7 that pertains to the same line with which she engaged waiting contact pertains. When the wipers 18, 19 are engaged with such waiting contacts 6, l, a circuit is closed that is traceable from the battery W, through the extreme right hand armature switch of sluggishly operating relay 71 and its alternate contact, the wiper Q8, she suiting; contact 54, the lower wind ingof he relay T2, the righe hand ermrv sr. tch of relay 78 and its normal conmec, the lower armature switch of relay 79 and normal f0llOW-l'lp contact, thewiper 1f), the waiting contact 7 engaged thereby, the waiting" Contact 63, the wiper 59 engaged therein, the switch spring 80 and the contact which was engaged thereby when the ratchet wheel 60-1noved its first step from normal, the v indingof release magnet 62, back to the battery 7 7. The release magnet 52 will withdraw the actuating; puwl operated. by the motor magnet 61 whereupon the wiper 59 will be restored to normal, and when this wiper 59 reaches normal the switch springs 76 and 80 are removed from engagement with their contacts whereupon the circuit f the mooor magnet 25 is opened one the wipers 18, 19 are caused to remain i with the waiting contacts 6, Y of the is i may 42 t at is le from the grounded battery 64-, the upper winding of this relay, ehe upper. or-

ineture switch or will? relay and its ulternetewiper 1 the waiting contact ofze contact the 1, urincure switch of the relay 68, ioez-s 8, 9, the ed ihese ground. Circuit is established for the motor magnet 58 traceable from the grounded battery 64, the winding of this motor magnet, the wiper 49, the waiting contact 55, the left hand alternate contact of the intermediate armature switch of relay 72 to. ground whereby the motor magnet 58 is operated to move the wipers 45 to 50 from the waiting contacts 5156 with which they were in'engage'ment and into engagement with another set of waiting contacts 51--56 that pertain to an unemployed link connector 16, 17.

If the line wanted is busy-circuit is es--. tablished for the relay 81 which is traceable from the grounded battery 64, the left hand armature switch of relay 78 and its contact, the winding of relay 81, the uppermost armature switch of relay 79 and its normal contact, the wiper 18, the waiting contact 6 engaged thereby, another waiting contact 6 connected with the wanted line and there engaged either by another wiper V 18 or another wiper 8 accordingly as the wanted line is a previously called line er a previously calling line, through both sides of the wanted previously busy llne, the

waiting contact 7 complemental to the second waiting contact 6, thence to the grounded intermediate armature switch of the relay 72 by way of one or the other of the windings 78 as will be apparent. The relay 81 being thus energized opens the circuit for the ringing current generator 82 so that current from this generator cannot find passage to the wa'nted previously busy line until the relay 1 is deenergized, an occurrence which arises when the telephone receiver at the wanted station is restored to its switch hook whereupon the bell at this wanted station is rung and the party there again responds, the signaling current finding passage from the grounded generator 82, the lower winding of the ringing relay 79, the armature switch of the now deenergized relay 81 and its then engaged contact, the alternate contact of the right hand armature switch of relay 78. this armature switch, the lowermost armature switch of relay 79 and its normal follow-up contact,- the wiper 19, the waiting contact 7, both sides of the wanted line, the bell bridge at the substation of the wanted line, the waiting contact 6, the wiper 18, the uppermost armature switch of the relay 79 and its normal contact, this armature switch and normal contact serving to shunt the upper winding of the relay 79, the winding of relay 81, the left hand armature switch of relay 78 and its engaged contact, to the grounded battery 64. The relays 79 and 81 called station, but when the low resistance bridge including the receiver and t'ransmitter at the called. station is substituted for the comparatively high resistance signal bell bridge thereat current from thegenerator 82 is sufiiciently increased to energize the relay 79, the circuit for the relay 81 being then open at the normal contact of the upper armature switch of the relay 79. When the relay 79 is thus energized another holding-circuit is established. forthe relay 78 which is traceable from the grounded so battery 64 through the left hand armature switch of relay 78 and its contact, the Winding of relay 81, the upper winding of relay. 79, the wipers-18, 19 and the contacts 6, 7

.of the called line, both sides of the called 85 line now connected through the telephone receiver and transmitter at the called substation thereof, the lower armature switch of relay 79 and its alternate contact, the right hand winding of relay 78, the right so hand alternate contact of the intermediate I armature switch of the relay 72, this arma ture switch, to ground. The circuit thus traced also constitutes a holding circuit for the relays 7 9-and 81, the relay 81 now operating to remove the generator 82 from circuit with the wanted line. The armature switches 79, by engaging their alternate contacts, telephonically complete the normally separated sections of the link conductors 16, 17. Current is supplied to the transmitters at the connected stations by a path a section of which is traceable fr m the grounded battery 64, through the upperl winding of the relay 72, the uppermostioa most armature switch of relay 72, the alterllo' nate contact of this switch, the left hand winding of relay 78, the right hand alter nate contact of the intermediate armature switch of relay 72, this intermediate armature switch, to ground, current from battery 64 thus finding passage in both directions through the upper winding of relay 72 so that this relay will remain energized until both subscribers have restored their re ceivers upon their switch hooks.

It will be observed that the wipers of the electro-magnetic connector switching devices at 20, 21 and 22 are always in engagement with some waiting contacts, when such wipers are at rest, whether the wipers are in or out of circuit, the system of my inven tion avoiding the necessity of restoring mechanism for the switches.

It will be observed that each of the lin k connectors includes but two conductors which are talking sioles by means of which the necessary switching functions nerg. iormecl, no third conductor being required in any of the link connectors for this 1) KT- pose. It Will also he observedthat the seconcl'linl; connectors (16, I7) seek the fi'st link connectors instead of being sought by the first link connectors. it will also be observed that the relays 38 and nornmll v ope ate to s parate the link connectors with whlch they are associated each into two telephonicnlly distinct sections, these reiays being energized by the ceiling snhscriber at the proper time, telephoniczllly to complete their associate link connectors Where Wiper contacts 8, 9, 14-, 15, ancl 18, 19 may remain in connection with the waiting contools with which they were brought into gagcnient whereby stepping up ineehnnis n and release mechanism individual to the chiferent link comiectors are dispensed with.

lVhile I have heroin shown and particw lzirly described the prNerr-ed emboclimen e1? my invention I do not Wish "to be limited to the precise consruction and circi it arrange ment shown as changes may rea he made ithout departing from the spin o 1n invention nor do Z Wish to he linn ,4 lines; electro-inngneiic connecor swi m devices for extending Stllil link connecto s that have become connected with calling: lines and indi'virlnni tothe linl-z connectors of said group; a calling snbr iher controlleil master switching device common to and i iercl'mngeoh y es ociniorl with the link nectors of said rcnp and ml control of the 0 swi'cchingg (lOV niech an 1, 111 f0 r connc there ink for effecting con! lines; CZLlllT j snhscril lllflflllP-r. hector .jwii h tending link (GRPE' 'iOFS come connected with calling lin viiliml to the link connccto a master switching interehangeahlv ass-00hr. r connectors of 'cl gronn the control of the opera c ona upsWi'i-c "en eonnece lcvi ope A r'elephone exchzr g no "telephone lines extending to on exchange; a grong for elicctii connecion bet lines; calling sni roli e. elnnagneuc connector switching devices for extending; Sfilfl. linic conne s H i" v connected with celhn con e riilnnl in the link connec n c; lling subscriber switching liGYlCB connnon t ch-iinsrez ihly :issocimed with the tors in s:

ll group and hihii control of the mvitching rlevi mechanism i selecting switching devices which are i. A tBlQPlIOlli': c change ephone lines exec 11 exchange; a

group master inter contitel to wl .L 1 i w eeling" 1 with the link coinicemrs oi suii taking part ii the i of lil con devices; mil calling snh, seeking; up

izin the con 3,

switching moi nzinisin from snhsi-zihicns n: connectors cnge s -jrstcni including devices 1 hccmne conneci v ni liY1 lnnl he the i1" calling subs in" (levie group a o minor ing enh- 'i-ching connector operate-i.

- cinoii v stations w 7 (f iini: connectors heiween telephone l leciroelm a re

nectors of said {group and taking part in the control 011' the operation of said connector switching devices; and calling subtelephone lines extending from substations to "an exchange; a group of link connectors forefiecting connection between telephone lines; calling subscriber controlled electromagnetic connector switching devices for extending said linkconnectors that have be-- come connected with calling lines and indi vi'dual to the link connectors of said group; a calling subscriber controlled master switching device common to and interchangeably associated with the link con nectorsof said group and taking part in the control of the operation of said connector switching devices; and calling subscriber. controlled setting up switching mechanism 'of different sets for extending said telefor selecting the connector switching devices which are to be operated.

8. A telephone exchange system including telephone lines extending from substations to anexchange; means for applying signaling current to desired lines; electromagnetic means governed by desired llnes for withholding the application of signaling current thereto when said desired lines are previouslybusy and for effecting the application of signaling current to such lines when restored to normal at their substations; link connectors for oining telephone lines in conversation; switching mechanism for normally dividing the same into sections; and

additional electro-magneticmeans operated by signaling current when flowing to desired lines whose stations have responded for operating said switching mechanism telephonically to join said sections.

9. A telephone exchange system including a group of telephone conductor sections; electromagnetic connector switching devices for extending said telephone conductor sections; electromagnetic setting up switching mechanism at the exchange and common to the electromagnetic connector switching devices for selecting the connector switching devices which are to be operated; means at the stations of the lines which are operable at calling stations for actuating the setting up switching mechanism; and a calling subscriber controlled master switching device common to and interchangeably associated with the telephone conductor sections of said group and through which master switching device the setting up switching mechanism operates.

10.,A telephone exchange system including telephone lines extending from substations to an exchange; electromagnetic connector switching devices for extending the telephone lines and including wipers and master switching device common to and interchangeably associated with the telephone.

conductor sections of said group and through which master switching device the setting up switching mechanism operates.

11.,' A telephone exchange system including telephone lines extending to an exchange; successive sets of conductor sec- .tions; electromagnetic connector switching devices pertaining to the conductor sections phone conductor sections; a master switch for each set of telephone conductor sections cooperate with the selector switch it has so I lected to operate the electromagnetic switching device coupled with this selected selector switch.

12. A telephone exchange system including telephone lines extending to an exchange; a plurality of sets of telephone conductor sections; electromagnetic connector switching devices pertaining to the conductor sections of different sets for extending said telephone conductor sections; a master switch" for each set of electromagnetic connector switching devices and provided with means for effecting its association with an unemployed electromagnetic connector switching device in the set to which it pertains; a setting up switch in interchangeable relation with the, master switches and provided with means for bringing it into association with an unemployed master switch to bring the setting up switch into association with the electromagnetic connector switching device coupled with such unemployed master switch; and

subscriber controlled, means at the stations of the telephone lines and operated at calling stations for operating the setting up switch.

13. A telephone exchange system including telephone lines extending to an exchange; a plurality of sets of line extending electro-magnetic connector switching devices; a master switch for each set of electromagnetic connector switching devices and provided with means for efi'ecting its association with anunemployed electro-magnetic connector switching device in the set to which it pertains; a setting up switch in interchangeable relation with the master switches and provided with means for bringing it into association with an unemployed master switch to bring the setting up switch into association with the electro-magnetic connector switching device coupled with such unemployed master switch; and subscriber controlled means at the stations of the telephone lines and operated at calling stations for operating the setting up switch.

14. A telephone exchange system including telephone lines extending to an exchange; electro-magnetic line extending connector switching devices; a master switch provided with means for effecting its association with an unemployed electro-magnetic connector switching device; a setting up switch operatively associated by the master switch with the electro-magnetic connector switchin'g device coupled with such master switch; and subscriber controlled means at the stations of the telephone lines and operated at calling stations for operating the setting up switch.

15. A telephone exchange system including telephone lines extending to an exchange; link connectors; calling subscriber controlled switching mechanism for connecting link connectors with calling lines; succeeding link connectors; and means for connecting a succeeding link connector with a preceding link connector and operating to place a free one of the first mentioned link connectors in condition to be connected with another calling line.

16. A telephone exchange system including telephone lines extending to an exchange; link connectors; calling subscriber controlled switching mechanism for connecting link connectors with calling lines; sucv ceeding link connectors;and subscriber controlled means for connecting a succeeding link connector with a preceding link connector and operating to place a free one of the first mentioned link connectors in condition to be connected with another calling line.

17. A telephone exchange system including telephone lines extending to an exchange; electro-magnetic line extending connector switching devices; a setting up switch; means for effecting the association of the setting up switch with an unemployed electro-magnetic line extending connector switching device; and mea s for operating the setting up switch.

In witness whereof, I hereunto subscribe my name this thirty-first day of March,

r ELMER R. CORWIN. Witnesses:

G. L. CRAGG, E. L. WHITE. 

